I need to get arrow key presses, but keyDown won't call (Swift)

Subclassing is less difficult than it seems.

Short tutorial:

General assumption: keystrokes are going to be received in the view of a NSViewController subclass and to be processed in the view controller class

• Create a new Cocoa Class named MyView as a subclass of NSView

• Replace the contents of the created class with

  import Cocoa let leftArrowKey = 123 let rightArrowKey = 124 protocol MyViewDelegate { func didPressLeftArrowKey() func didPressRightArrowKey() } class MyView: NSView { var delegate : MyViewDelegate? override func keyDown(event: NSEvent) { let character = Int(event.keyCode) switch character { case leftArrowKey, rightArrowKey: break default: super.keyDown(event) } } override func keyUp(event: NSEvent) { let character = Int(event.keyCode) switch character { case leftArrowKey: delegate?.didPressLeftArrowKey() case rightArrowKey: delegate?.didPressRightArrowKey() default: super.keyUp(event) } } override var acceptsFirstResponder : Bool { return true } } 

  • Change the class of the view of the ViewController in Interface Builder to MyView

  • In the ViewController class add the protocol MyViewDelegate- for example

    class ViewController: NSViewController, MyViewDelegate { 

  • In viewDidLoad() add

    let view = self.view as! MyView view.delegate = self self.nextResponder = view 

  • Implement the following delegate methods and add your code to switch the image(s)

    func didPressLeftArrowKey() { println("didPressLeftArrowKey") // process keystroke left arrow } func didPressRightArrowKey() { println("didPressRightArrowKey") // process keystroke right arrow } 

The delegate methods are called when the appropriate arrow keys are released